The book deals with the complex notion of process worked out by Alfred N. Whitehead, a notion that includes his deep revision of the concepts of time and space. Throughout his whole career, Whitehead emphasized the im­portance of process for the ac­count of reality. The book dis­cusses Whitehead’s concept of process starting from his works in mathematics, logic and epis­temology of the natural sciences, in order to pave the way for a better understanding of White­head’s speculative philosophy. The focus is on the relationship between concrescence and tran­sition, seen as deeply correlated and reciprocally determined. In this perspective, the book offers a reinterpretation of Whitehead’s most enigmatic proposal: the event of subjectivity interpreted as a process of subjectivation. This poses the problem of the endurance of subjectivity. The book suggests that this problem is solved by Whitehead through is appropriation of Plato’s notion of chora, seen as the “place” of a processual subject.